The goal of the New York City Sickle Cell Implementation Science Consortium (NYCSIS) is to leverage a `learning laboratory' of six hospitals and eleven ambulatory practices within the Mount Sinai Health System (MSHS) to improve penetration of best practices for adults and adolescents with Sickle Cell Disease (SCD). New York City has one of the largest SCD populations in the US, and MSHS provides SCD care to over 700 adults and adolescents. The NYCSIS team and its community partners have identified three critical knowledge-to-action gaps: 1) improving pain management in adult emergency departments (ED), 2) reconnecting individuals who as adults use only the ED back into longitudinal care and 3) delivering comprehensive care in low-density (i.e. smaller numbers of people with SCD) settings with limited access to expert SCD hematologists. Our setting and research infrastructure position us well to address these three issues as MSHS has a robust multi-site emergency medicine research infrastructure (with access to hundreds of adults with SCD who do not utilize primary care) as well as low-density hospitals and community health centers where the full complement of experts (e.g. hematologists and other specialists) are not available. We propose four aims. Aim 1: Conduct a whole-community needs assessment to a) identify additional areas of need, and b) for the three interventions already developed, to understand barriers and facilitators to scaling and implementing them at each care locations; Aim 2: Design implementation research studies that address the identified issues of importance; Aim 3: Participate in the development of the SCD registry in collaboration with the Data Coordinating Center and NHLBI; and Aim 4: Conduct implementation studies that test multi-modal, multi-sector interventions to a) improve emergency care of SCD pain, b) reconnect unaffiliated adults into comprehensive care and c) deliver comprehensive care in low SCD density settings. The NYCSIS team has the resources and community network to rigorously collect and integrate registry data with other U01 sites, and to execute implementation studies that address the needs of urban SCD populations, particularly in low-density care settings with limited access to SCD experts.